671n trouble

[micky]

Last trip everything was fine on a 3 hour trip, today when i went to start the stbd engine it cranked but wouldn't start unles I would put the throttle completely forward and when it started the rpms were fluctuating between 650-400. Took the boat out and that engine would not go more than 1200 rpms, came back to the dock and dissasembld the racor bowl and it was clogged with algae and also replaced the the copper fuel line from the tank to the racor with new hose. Now the engine starts but I have to give it some gas like if it had a carb. Could it be a rack adjustment?? The other engine sounds stronger and it has more power. When I put it in gear at the dock it sounds like it bogs down.

 

[saltshaker]

Did you replace the spin on or cartridge filter?

 

[micky]

Yeah, I also replaced that one. The old one was clean but installed a new one.

 

[Finalee]

Sure sounds like its starved for fuel. Algae clogs filters quick. Be certain there is not a slug of it blocking the tank intake. Work your way forward verifying unobstructed fuel flow. As mentioned by others , try running off an external fuel source to verify problem.

 

[davidwigler]

Replace the Racors with these and you will know when you need a filter change:

http://www.sbmar.com/smx-fueltration-system-kits.php

Or at least install one of the bulk separator kits before your Racors and you may never need to clean them again.

Then use up all your old fuel and enjoy it.

 

[davidwigler]

Also, do you have a fuel manifold? Swap to the other tank and confirm the problem goes away. Remember to set your fuel supply and return valves to the same tank.

 

[jim rosenthal]

Does he need to treat the tanks with biocide? sounds like he might.

 

[Boatsb]

New filters will not solve the problem. Clean fuel will. If the pickup is clogged. The valve has a clump caught in it or some other restrictions in the lines no filter will fix that.

Your racors seem to be doing their job. My 8v53s had 2 spin ons from the factory. Plus racors are on the he tank end. Are you sure you changed all the filters and did you check if the lines are clear?

 

[micky]

I replaced the hose from the tank to the racor, so that's not the problem. I'm going to replace the check valve and the small gasket where the check valve is on the racor, maybe it's not sealing well and that's why it's so hard to start unless I advance the throttle.

 

[Genesis]

You may have a piece of trash (anything from biological growth to actual trash) plugging the pickup or the lines between the tank and the primary. Pull vacuum on the fuel line on the output of the RACOR and see whether there is meaningful resistance to the flow of fuel (there shouldn't be.) If there is, find someone with a vacuum tank, pull a very sizeable vacuum on it, attach to the outlet and "hit it", attempting to suck the obstruction through with a hard vacuum. If it's biological there's a good chance it will come through the line that way and into the filter where it is trapped and removed.

If not you can try blowing it back into the tank but the problem with doing that (and why you don't do that first!) is that if you unplug it that way it's still in there and will plug it up again. If you do use pressure be judicious -- the stock copper will take a good amount of pressure but they're not impervious to being blown out.

Biocide will not break up accumulated stuff, in fact, if there is active growing biological bacteria in the interface between water and fuel (bacterial growth requires some water in the fuel -- not a lot, but some) biocide will kill it and it will fall to the bottom of the tank where it can get into the pickup, making the clog problem worse.

The fuel pump may also be bad but before you pull that I'd check for restriction and serious air leaks on the suction side of the fuel system.

 

[saltshaker]

Check you fuel shutdown solenoid. Make sure it returns to the fully open position after shutdown.

 

[micky]

Check you fuel shutdown solenoid. Make sure it returns to the fully open position after shutdown.

There's no shutdown solenoid, it has a pull cable like the emergency shutdown.

 

[Boatsb]

Is that fully open? That shuts off the fuel to the engine.

 

[micky]

Is that fully open? That shuts off the fuel to the engine.

Yes it is. I'm going to clan the tanks and change the check valve on the racor and will report back.

 

[spartonboat1]

This a just sayin' post. My genset all of a sudden would not start, or would start and run for 10-15 secs max. Due to personal situation, did no running that year, so not huge issue. I purchased a vacuum/pressure gage and tested before and after the pump (and pulled and dis-assembled/re-assembled pump). By accident I discovered one hose line fitting on the input side the to pump was ever so slightly loose. Once confirmed fully tight, the genny took off and starts quickly since then. May have been a growing issue for years, as starts better now that had been for a couple years.

This post is not to detract from the occlusion issues (blocking valves, fittings, pickup, etc), but to re-inforce that you have strong vacuum from the fuel line to the fuel pumps and all points. A very slight loss of vacuum could contribute to the overall issue, after all blocking is accounted for.

 

[micky]

Cleaned the tank and now it accelerates normal. The hard to start engine was the check valve on the racor, the seal for the small ball was bent in 2 places, replaced it and all is good now.

 

[spartonboat1]

spartonboat1

Cleaned the tank and now it accelerates normal. The hard to start engine was the check valve on the racor, the seal for the small ball was bent in 2 places, replaced it and all is good now.

Yee-Hah...nice to have a straightforward cure!